1. Field of the Invention
The present invention is related to determining sleepiness and, in particular, to determining sleepiness based on motion analysis of a face of a target person.
2. Description of Related Art
Sleeping by a driver of a moving vehicle is undeniably dangerous. Proposals to prevent sleeping having included suggestions for devices for capturing a face of the driver by use of a camera mounted in the vehicle and for processing the obtained image to determine a degree of sleepiness. Usually, in such devices, the eyes of the driver are specified from the obtained image, an opening and line of sight of the eyes is detected from the image, and the presence or absence of sleepiness is determined from the detection result. For example, a device in which an opening of eyes is detected sequentially to determine whether a target person is asleep more precisely has been suggested in accordance with JP-A-11-66304.
However, problems with the above described method exist in that eye movement often changes in accordance with situation where a vehicle is traveling. For example, when the sunlight enters the eyes of the driver, the driver squints in many cases regardless of a level of sleepiness. Other eye based indications such as the frequency of mirror checking or confirmation by the driver on an expressway are unreliable since indications on a highway, busy town or city can differ from a mirror checking frequency that might be used by the same driver on a small road or in a small town regardless of sleepiness.
Still further complicating detection is the problem that eye movement relates generally to a sleepiness level of the target person directly, but as described above, many disturbances to the determination of a degree of sleepiness occur. Therefore, many countermeasures are needed for determining a degree of sleepiness from only eyes.